Thursday, January 8, 2009

B2 Used d6 Hit Dice

Here's an interesting statistical discovery I made last night -- take a look at D&D Module B2, The Keep on the Borderlands. Ostensibly this was written for the Holmes Basic set, and was included in many boxed version of that set. Supposedly in that set Hit Dice are supposed to represent 8-sided dice.

But if you take a close look at the monsters in B2, you'll see they were really developed presuming 6-sided Hit Dice; that is, it's really made for Original D&D, pre-Supplement I (Greyhawk, which revised hits to d8 dice). Here's some examples where it's easiest to see. We'll assume our hypothesis (B2 hit dice are d6; average roll 3.5) and see if things are consistent.

H. Bugbear Lair. HD 3+1 -> expect 11.5 hit points for a normal bugbear. Listed guard/male equivalent hit points are: 11, 12, 12, and 10, so that's very consistent. Key piece of evidence: In area #41 there's a 14 hp bugbear described as "the big bugbear"; if HD were d8 then he would be below average; but if HD are d6 then he is indeed bigger than expected.

Now, Gary did a couple of recognizable things when setting hit points (familiar from his later writings), like, if in doubt he'd usually set monster hit points a little bit above the expectation. Most solo "boss" monsters he sets at Max or Max-1 possible hit points (and again you see that a lot in B2, recognizing that hit dice are d6 here).

But what he never did in B2 is set any monster hit points over the max possible with d6 hit dice. For example, there are no kobolds with 4 hp. There are no normal orcs with 7 or 8 hit points. The same can't be said of Mike Carr's module B1, which does in fact list some 4-hp kobolds and 8-hp orcs (for example), demonstrating that the B1 module was in fact developed using post-Greyhawk, Holmes Basic rules.

(Note: A more formal demonstration could be done in a comprehensive spreadsheet, listing all hit points in the module, and running an SSE "sum squared error" analysis on each hypothesis and seeing which comes out closer -- much as I did for the AD&D multiclassing problem: http://deltasdnd.blogspot.com/2008/04/multiclass-hit-points.html. I don't have the time now to do that more formal demonstration, but I'm very confident of what the results would be if it was done. B2 was developed and published assuming d6 Hit Dice, not truly in accordance with the Holmes Basic D&D rules.)

Skeletons and Zombies, in OD&D, are ½ and 1 HD respectively, so the B2 entries for those particular monsters does not actually follow the original edition rules. Nevertheless a very insightful post which leaves me thinking that perhaps the module was in fact “made” for Basic, but when the actual HP rolling came around, someone assumed d6 for hits and we see the results. Whether Gary rolled these, or some TSR flunky, we might never know.

Dave, good catch about the undead hit dice. However, I don't think anyone literally "rolled" the hit points in B2. (a) Gary wrote more than once about how he just picked hp by fiat that served the adventure (e.g., as I mentioned for the solo boss monsters), (b) the hit points in B2 are set equally, near the average, for large groups of monsters (which could not be the result of actually rolling them all).

"Skeletons and Zombies, in OD&D, are ½ and 1 HD respectively, so the B2 entries for those particular monsters does not actually follow the original edition rules."

The comment about 1/2 hit die skeletons might expalin the experience point example on page 3 of my copy, where each skeleton is only worth 5 experience points, which is what the Greyhawk supplement and some later rules use.

And why Zombies are 2 hit die in many other rules but easier to turn than ghouls who are also 2 hit die. The turn undead chart in most rules being based off OD&D.